This invention relates generally to the handling of material and more particularly to the handling of material such as ore or rock in mines.
It is commonplace on mines to transfer ore or rock from an underground loading flask to a skip which is then hoisted to surface. In modern installations the transference of the material is effected substantially automatically.
The skip referred to is suspended from a cable in a shaft and the loading station may be a considerable distance below surface. In the loading process a rapid transference of material takes place and this may be likened to an impulse loading of the skip. As a consequence the skip is subjected to oscillations and eventually settles at a point which, depending on its final load, can be in the order of metres below the position at which loading commenced. The flask on the other hand is stationary and consequently a substantial gap can be formed between the mouth of the skip and the discharge end of the flask. Material destined for the skip may, in this way, not enter the mouth and instead fall down the shaft. This material is highly hazardous to personnel and any installation or equipment at a lower level.
To counteract the danger of falling material use has been made of a spillage bin immediately below the skip. It does happen however that the spillage bin can be filled with waste material in which event the skip may inadvertently be brought to rest on the top of this material. This can lead to a slack cable condition which in turn can result in cable failure.
Various approches to the problem are to be found in the disclosures in German Pat. Nos. 1215884, 718546, 876901 and 392005, and in U.S. Pat. Nos. 3,702,140, 1,708,925, 2,737,308 and 3,767,074.
The first mentioned specification describes an arrangement wherein an intermediate funnel, which moves together with the skip, is used to transfer material from a primary bunker to the skip. The primary bunker does not move. This arrangement, in practice, leads to considerable spillage of ore down the shaft and is not satisfactory.